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evoked.py
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evoked.py
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# -*- coding: utf-8 -*-
# Authors: Alexandre Gramfort <alexandre.gramfort@inria.fr>
# Matti Hämäläinen <msh@nmr.mgh.harvard.edu>
# Denis Engemann <denis.engemann@gmail.com>
# Andrew Dykstra <andrew.r.dykstra@gmail.com>
# Mads Jensen <mje.mads@gmail.com>
# Jona Sassenhagen <jona.sassenhagen@gmail.com>
#
# License: BSD (3-clause)
from copy import deepcopy
import numpy as np
from .baseline import rescale
from .channels.channels import (ContainsMixin, UpdateChannelsMixin,
SetChannelsMixin, InterpolationMixin)
from .channels.layout import _merge_ch_data, _pair_grad_sensors
from .defaults import _EXTRAPOLATE_DEFAULT, _BORDER_DEFAULT
from .filter import detrend, FilterMixin
from .utils import (check_fname, logger, verbose, _time_mask, warn, sizeof_fmt,
SizeMixin, copy_function_doc_to_method_doc, _validate_type,
fill_doc, _check_option, ShiftTimeMixin, _build_data_frame,
_check_pandas_installed, _check_pandas_index_arguments,
_convert_times, _scale_dataframe_data, _check_time_format)
from .viz import (plot_evoked, plot_evoked_topomap, plot_evoked_field,
plot_evoked_image, plot_evoked_topo)
from .viz.evoked import plot_evoked_white, plot_evoked_joint
from .viz.topomap import _topomap_animation
from .io.constants import FIFF
from .io.open import fiff_open
from .io.tag import read_tag
from .io.tree import dir_tree_find
from .io.pick import pick_types, _picks_to_idx
from .io.meas_info import read_meas_info, write_meas_info
from .io.proj import ProjMixin
from .io.write import (start_file, start_block, end_file, end_block,
write_int, write_string, write_float_matrix,
write_id, write_float, write_complex_float_matrix)
from .io.base import TimeMixin, _check_maxshield
_aspect_dict = {
'average': FIFF.FIFFV_ASPECT_AVERAGE,
'standard_error': FIFF.FIFFV_ASPECT_STD_ERR,
'single_epoch': FIFF.FIFFV_ASPECT_SINGLE,
'partial_average': FIFF.FIFFV_ASPECT_SUBAVERAGE,
'alternating_subaverage': FIFF.FIFFV_ASPECT_ALTAVERAGE,
'sample_cut_out_by_graph': FIFF.FIFFV_ASPECT_SAMPLE,
'power_density_spectrum': FIFF.FIFFV_ASPECT_POWER_DENSITY,
'dipole_amplitude_cuvre': FIFF.FIFFV_ASPECT_DIPOLE_WAVE,
'squid_modulation_lower_bound': FIFF.FIFFV_ASPECT_IFII_LOW,
'squid_modulation_upper_bound': FIFF.FIFFV_ASPECT_IFII_HIGH,
'squid_gate_setting': FIFF.FIFFV_ASPECT_GATE,
}
_aspect_rev = {val: key for key, val in _aspect_dict.items()}
@fill_doc
class Evoked(ProjMixin, ContainsMixin, UpdateChannelsMixin, SetChannelsMixin,
InterpolationMixin, FilterMixin, TimeMixin, SizeMixin,
ShiftTimeMixin):
"""Evoked data.
Parameters
----------
fname : str
Name of evoked/average FIF file to load.
If None no data is loaded.
condition : int, or str
Dataset ID number (int) or comment/name (str). Optional if there is
only one data set in file.
proj : bool, optional
Apply SSP projection vectors.
kind : str
Either 'average' or 'standard_error'. The type of data to read.
Only used if 'condition' is a str.
allow_maxshield : bool | str (default False)
If True, allow loading of data that has been recorded with internal
active compensation (MaxShield). Data recorded with MaxShield should
generally not be loaded directly, but should first be processed using
SSS/tSSS to remove the compensation signals that may also affect brain
activity. Can also be "yes" to load without eliciting a warning.
%(verbose)s
Attributes
----------
info : dict
Measurement info.
ch_names : list of str
List of channels' names.
nave : int
Number of averaged epochs.
kind : str
Type of data, either average or standard_error.
comment : str
Comment on dataset. Can be the condition.
data : array of shape (n_channels, n_times)
Evoked response.
first : int
First time sample.
last : int
Last time sample.
tmin : float
The first time point in seconds.
tmax : float
The last time point in seconds.
times : array
Time vector in seconds. Goes from ``tmin`` to ``tmax``. Time interval
between consecutive time samples is equal to the inverse of the
sampling frequency.
%(verbose)s
Notes
-----
Evoked objects contain a single condition only.
"""
@verbose
def __init__(self, fname, condition=None, proj=True,
kind='average', allow_maxshield=False,
verbose=None): # noqa: D102
_validate_type(proj, bool, "'proj'")
# Read the requested data
self.info, self.nave, self._aspect_kind, self.comment, self.times, \
self.data = _read_evoked(fname, condition, kind, allow_maxshield)
self._update_first_last()
self.verbose = verbose
self.preload = True
# project and baseline correct
if proj:
self.apply_proj()
@property
def kind(self):
"""The data kind."""
return _aspect_rev[self._aspect_kind]
@kind.setter
def kind(self, kind):
_check_option('kind', kind, list(_aspect_dict.keys()))
self._aspect_kind = _aspect_dict[kind]
@property
def data(self):
"""The data matrix."""
return self._data
@data.setter
def data(self, data):
"""Set the data matrix."""
self._data = data
@verbose
def apply_baseline(self, baseline=(None, 0), *, verbose=None):
"""Baseline correct evoked data.
Parameters
----------
%(baseline_evoked)s
Defaults to ``(None, 0)``, i.e. beginning of the the data until
time point zero.
%(verbose_meth)s
Returns
-------
evoked : instance of Evoked
The baseline-corrected Evoked object.
Notes
-----
Baseline correction can be done multiple times.
.. versionadded:: 0.13.0
"""
self.data = rescale(self.data, self.times, baseline, copy=False)
return self
def save(self, fname):
"""Save dataset to file.
Parameters
----------
fname : str
The name of the file, which should end with -ave.fif or
-ave.fif.gz.
Notes
-----
To write multiple conditions into a single file, use
:func:`mne.write_evokeds`.
"""
write_evokeds(fname, self)
def __repr__(self): # noqa: D105
s = "'%s' (%s, N=%s)" % (self.comment, self.kind, self.nave)
s += ", [%0.5g, %0.5g] sec" % (self.times[0], self.times[-1])
s += ", %s ch" % self.data.shape[0]
s += ", ~%s" % (sizeof_fmt(self._size),)
return "<Evoked | %s>" % s
@property
def ch_names(self):
"""Channel names."""
return self.info['ch_names']
@property
def tmin(self):
"""First time point.
.. versionadded:: 0.21
"""
return self.times[0]
@property
def tmax(self):
"""Last time point.
.. versionadded:: 0.21
"""
return self.times[-1]
@fill_doc
def crop(self, tmin=None, tmax=None, include_tmax=True, verbose=None):
"""Crop data to a given time interval.
Parameters
----------
tmin : float | None
Start time of selection in seconds.
tmax : float | None
End time of selection in seconds.
%(include_tmax)s
%(verbose_meth)s
Returns
-------
evoked : instance of Evoked
The cropped Evoked object, modified in-place.
Notes
-----
%(notes_tmax_included_by_default)s
"""
mask = _time_mask(self.times, tmin, tmax, sfreq=self.info['sfreq'],
include_tmax=include_tmax)
self.times = self.times[mask]
self._update_first_last()
self.data = self.data[:, mask]
return self
@verbose
def decimate(self, decim, offset=0, verbose=None):
"""Decimate the evoked data.
Parameters
----------
%(decim)s
%(decim_offset)s
%(verbose_meth)s
Returns
-------
evoked : instance of Evoked
The decimated Evoked object.
See Also
--------
Epochs.decimate
Epochs.resample
mne.io.Raw.resample
Notes
-----
%(decim_notes)s
.. versionadded:: 0.13.0
"""
decim, offset, new_sfreq = _check_decim(self.info, decim, offset)
start_idx = int(round(self.times[0] * (self.info['sfreq'] * decim)))
i_start = start_idx % decim + offset
decim_slice = slice(i_start, None, decim)
self.info['sfreq'] = new_sfreq
self.data = self.data[:, decim_slice].copy()
self.times = self.times[decim_slice].copy()
self._update_first_last()
return self
@copy_function_doc_to_method_doc(plot_evoked)
def plot(self, picks=None, exclude='bads', unit=True, show=True, ylim=None,
xlim='tight', proj=False, hline=None, units=None, scalings=None,
titles=None, axes=None, gfp=False, window_title=None,
spatial_colors=False, zorder='unsorted', selectable=True,
noise_cov=None, time_unit='s', sphere=None, verbose=None):
return plot_evoked(
self, picks=picks, exclude=exclude, unit=unit, show=show,
ylim=ylim, proj=proj, xlim=xlim, hline=hline, units=units,
scalings=scalings, titles=titles, axes=axes, gfp=gfp,
window_title=window_title, spatial_colors=spatial_colors,
zorder=zorder, selectable=selectable, noise_cov=noise_cov,
time_unit=time_unit, sphere=sphere, verbose=verbose)
@copy_function_doc_to_method_doc(plot_evoked_image)
def plot_image(self, picks=None, exclude='bads', unit=True, show=True,
clim=None, xlim='tight', proj=False, units=None,
scalings=None, titles=None, axes=None, cmap='RdBu_r',
colorbar=True, mask=None, mask_style=None,
mask_cmap='Greys', mask_alpha=.25, time_unit='s',
show_names=None, group_by=None, sphere=None):
return plot_evoked_image(
self, picks=picks, exclude=exclude, unit=unit, show=show,
clim=clim, xlim=xlim, proj=proj, units=units, scalings=scalings,
titles=titles, axes=axes, cmap=cmap, colorbar=colorbar, mask=mask,
mask_style=mask_style, mask_cmap=mask_cmap, mask_alpha=mask_alpha,
time_unit=time_unit, show_names=show_names, group_by=group_by,
sphere=sphere)
@copy_function_doc_to_method_doc(plot_evoked_topo)
def plot_topo(self, layout=None, layout_scale=0.945, color=None,
border='none', ylim=None, scalings=None, title=None,
proj=False, vline=[0.0], fig_background=None,
merge_grads=False, legend=True, axes=None,
background_color='w', noise_cov=None, show=True):
"""
Notes
-----
.. versionadded:: 0.10.0
"""
return plot_evoked_topo(
self, layout=layout, layout_scale=layout_scale, color=color,
border=border, ylim=ylim, scalings=scalings, title=title,
proj=proj, vline=vline, fig_background=fig_background,
merge_grads=merge_grads, legend=legend, axes=axes,
background_color=background_color, noise_cov=noise_cov, show=show)
@copy_function_doc_to_method_doc(plot_evoked_topomap)
def plot_topomap(self, times="auto", ch_type=None, vmin=None,
vmax=None, cmap=None, sensors=True, colorbar=True,
scalings=None, units=None, res=64,
size=1, cbar_fmt="%3.1f",
time_unit='s', time_format=None,
proj=False, show=True, show_names=False, title=None,
mask=None, mask_params=None, outlines='head',
contours=6, image_interp='bilinear', average=None,
axes=None, extrapolate=_EXTRAPOLATE_DEFAULT, sphere=None,
border=_BORDER_DEFAULT, nrows=1, ncols='auto'):
return plot_evoked_topomap(
self, times=times, ch_type=ch_type, vmin=vmin,
vmax=vmax, cmap=cmap, sensors=sensors, colorbar=colorbar,
scalings=scalings, units=units, res=res,
size=size, cbar_fmt=cbar_fmt, time_unit=time_unit,
time_format=time_format, proj=proj, show=show,
show_names=show_names, title=title, mask=mask,
mask_params=mask_params, outlines=outlines, contours=contours,
image_interp=image_interp, average=average,
axes=axes, extrapolate=extrapolate, sphere=sphere, border=border,
nrows=nrows, ncols=ncols)
@copy_function_doc_to_method_doc(plot_evoked_field)
def plot_field(self, surf_maps, time=None, time_label='t = %0.0f ms',
n_jobs=1, fig=None, vmax=None, n_contours=21, verbose=None):
return plot_evoked_field(self, surf_maps, time=time,
time_label=time_label, n_jobs=n_jobs,
fig=fig, vmax=vmax, n_contours=n_contours,
verbose=verbose)
@copy_function_doc_to_method_doc(plot_evoked_white)
def plot_white(self, noise_cov, show=True, rank=None, time_unit='s',
sphere=None, axes=None, verbose=None):
return plot_evoked_white(
self, noise_cov=noise_cov, rank=rank, show=show,
time_unit=time_unit, sphere=sphere, axes=axes, verbose=verbose)
@copy_function_doc_to_method_doc(plot_evoked_joint)
def plot_joint(self, times="peaks", title='', picks=None,
exclude='bads', show=True, ts_args=None,
topomap_args=None):
return plot_evoked_joint(self, times=times, title=title, picks=picks,
exclude=exclude, show=show, ts_args=ts_args,
topomap_args=topomap_args)
@fill_doc
def animate_topomap(self, ch_type=None, times=None, frame_rate=None,
butterfly=False, blit=True, show=True, time_unit='s',
sphere=None):
"""Make animation of evoked data as topomap timeseries.
The animation can be paused/resumed with left mouse button.
Left and right arrow keys can be used to move backward or forward
in time.
Parameters
----------
ch_type : str | None
Channel type to plot. Accepted data types: 'mag', 'grad', 'eeg',
'hbo', 'hbr', 'fnirs_od, and 'fnirs_cw_amplitude'.
If None, first available channel type from ('mag', 'grad', 'eeg',
'hbo', 'hbr', 'fnirs_od, 'fnirs_cw_amplitude') is used.
Defaults to None.
times : array of float | None
The time points to plot. If None, 10 evenly spaced samples are
calculated over the evoked time series. Defaults to None.
frame_rate : int | None
Frame rate for the animation in Hz. If None,
frame rate = sfreq / 10. Defaults to None.
butterfly : bool
Whether to plot the data as butterfly plot under the topomap.
Defaults to False.
blit : bool
Whether to use blit to optimize drawing. In general, it is
recommended to use blit in combination with ``show=True``. If you
intend to save the animation it is better to disable blit.
Defaults to True.
show : bool
Whether to show the animation. Defaults to True.
time_unit : str
The units for the time axis, can be "ms" (default in 0.16)
or "s" (will become the default in 0.17).
.. versionadded:: 0.16
%(topomap_sphere_auto)s
Returns
-------
fig : instance of matplotlib.figure.Figure
The figure.
anim : instance of matplotlib.animation.FuncAnimation
Animation of the topomap.
Notes
-----
.. versionadded:: 0.12.0
"""
return _topomap_animation(
self, ch_type=ch_type, times=times, frame_rate=frame_rate,
butterfly=butterfly, blit=blit, show=show, time_unit=time_unit,
sphere=sphere)
def as_type(self, ch_type='grad', mode='fast'):
"""Compute virtual evoked using interpolated fields.
.. Warning:: Using virtual evoked to compute inverse can yield
unexpected results. The virtual channels have ``'_v'`` appended
at the end of the names to emphasize that the data contained in
them are interpolated.
Parameters
----------
ch_type : str
The destination channel type. It can be 'mag' or 'grad'.
mode : str
Either ``'accurate'`` or ``'fast'``, determines the quality of the
Legendre polynomial expansion used. ``'fast'`` should be sufficient
for most applications.
Returns
-------
evoked : instance of mne.Evoked
The transformed evoked object containing only virtual channels.
Notes
-----
This method returns a copy and does not modify the data it
operates on. It also returns an EvokedArray instance.
.. versionadded:: 0.9.0
"""
from .forward import _as_meg_type_inst
return _as_meg_type_inst(self, ch_type=ch_type, mode=mode)
@fill_doc
def detrend(self, order=1, picks=None):
"""Detrend data.
This function operates in-place.
Parameters
----------
order : int
Either 0 or 1, the order of the detrending. 0 is a constant
(DC) detrend, 1 is a linear detrend.
%(picks_good_data)s
Returns
-------
evoked : instance of Evoked
The detrended evoked object.
"""
picks = _picks_to_idx(self.info, picks)
self.data[picks] = detrend(self.data[picks], order, axis=-1)
return self
def copy(self):
"""Copy the instance of evoked.
Returns
-------
evoked : instance of Evoked
A copy of the object.
"""
evoked = deepcopy(self)
return evoked
def __neg__(self):
"""Negate channel responses.
Returns
-------
evoked_neg : instance of Evoked
The Evoked instance with channel data negated and '-'
prepended to the comment.
"""
out = self.copy()
out.data *= -1
out.comment = '-' + (out.comment or 'unknown')
return out
def get_peak(self, ch_type=None, tmin=None, tmax=None,
mode='abs', time_as_index=False, merge_grads=False,
return_amplitude=False):
"""Get location and latency of peak amplitude.
Parameters
----------
ch_type : 'mag', 'grad', 'eeg', 'seeg', 'ecog', 'hbo', hbr', 'misc', None
The channel type to use. Defaults to None. If more than one sensor
Type is present in the data the channel type has to be explicitly
set.
tmin : float | None
The minimum point in time to be considered for peak getting.
If None (default), the beginning of the data is used.
tmax : float | None
The maximum point in time to be considered for peak getting.
If None (default), the end of the data is used.
mode : {'pos', 'neg', 'abs'}
How to deal with the sign of the data. If 'pos' only positive
values will be considered. If 'neg' only negative values will
be considered. If 'abs' absolute values will be considered.
Defaults to 'abs'.
time_as_index : bool
Whether to return the time index instead of the latency in seconds.
merge_grads : bool
If True, compute peak from merged gradiometer data.
return_amplitude : bool
If True, return also the amplitude at the maximum response.
.. versionadded:: 0.16
Returns
-------
ch_name : str
The channel exhibiting the maximum response.
latency : float | int
The time point of the maximum response, either latency in seconds
or index.
amplitude : float
The amplitude of the maximum response. Only returned if
return_amplitude is True.
.. versionadded:: 0.16
""" # noqa: E501
supported = ('mag', 'grad', 'eeg', 'seeg', 'ecog', 'misc', 'hbo',
'hbr', 'None', 'fnirs_cw_amplitude', 'fnirs_od')
types_used = self.get_channel_types(unique=True, only_data_chs=True)
_check_option('ch_type', str(ch_type), supported)
if ch_type is not None and ch_type not in types_used:
raise ValueError('Channel type `{ch_type}` not found in this '
'evoked object.'.format(ch_type=ch_type))
elif len(types_used) > 1 and ch_type is None:
raise RuntimeError('More than one sensor type found. `ch_type` '
'must not be `None`, pass a sensor type '
'value instead')
if merge_grads:
if ch_type != 'grad':
raise ValueError('Channel type must be grad for merge_grads')
elif mode == 'neg':
raise ValueError('Negative mode (mode=neg) does not make '
'sense with merge_grads=True')
meg = eeg = misc = seeg = ecog = fnirs = False
picks = None
if ch_type in ('mag', 'grad'):
meg = ch_type
elif ch_type == 'eeg':
eeg = True
elif ch_type == 'misc':
misc = True
elif ch_type == 'seeg':
seeg = True
elif ch_type == 'ecog':
ecog = True
elif ch_type in ('hbo', 'hbr', 'fnirs_cw_amplitude', 'fnirs_od'):
fnirs = ch_type
if ch_type is not None:
if merge_grads:
picks = _pair_grad_sensors(self.info, topomap_coords=False)
else:
picks = pick_types(self.info, meg=meg, eeg=eeg, misc=misc,
seeg=seeg, ecog=ecog, ref_meg=False,
fnirs=fnirs)
data = self.data
ch_names = self.ch_names
if picks is not None:
data = data[picks]
ch_names = [ch_names[k] for k in picks]
if merge_grads:
data, _ = _merge_ch_data(data, ch_type, [])
ch_names = [ch_name[:-1] + 'X' for ch_name in ch_names[::2]]
ch_idx, time_idx, max_amp = _get_peak(data, self.times, tmin,
tmax, mode)
out = (ch_names[ch_idx], time_idx if time_as_index else
self.times[time_idx])
if return_amplitude:
out += (max_amp,)
return out
@fill_doc
def to_data_frame(self, picks=None, index=None,
scalings=None, copy=True, long_format=False,
time_format='ms'):
"""Export data in tabular structure as a pandas DataFrame.
Channels are converted to columns in the DataFrame. By default,
an additional column "time" is added, unless ``index='time'``
(in which case time values form the DataFrame's index).
Parameters
----------
%(picks_all)s
%(df_index_evk)s
Defaults to ``None``.
%(df_scalings)s
%(df_copy)s
%(df_longform_raw)s
%(df_time_format)s
.. versionadded:: 0.20
Returns
-------
%(df_return)s
"""
# check pandas once here, instead of in each private utils function
pd = _check_pandas_installed() # noqa
# arg checking
valid_index_args = ['time']
valid_time_formats = ['ms', 'timedelta']
index = _check_pandas_index_arguments(index, valid_index_args)
time_format = _check_time_format(time_format, valid_time_formats)
# get data
picks = _picks_to_idx(self.info, picks, 'all', exclude=())
data = self.data[picks, :]
times = self.times
data = data.T
if copy:
data = data.copy()
data = _scale_dataframe_data(self, data, picks, scalings)
# prepare extra columns / multiindex
mindex = list()
times = _convert_times(self, times, time_format)
mindex.append(('time', times))
# build DataFrame
df = _build_data_frame(self, data, picks, long_format, mindex, index,
default_index=['time'])
return df
def _check_decim(info, decim, offset):
"""Check decimation parameters."""
if decim < 1 or decim != int(decim):
raise ValueError('decim must be an integer > 0')
decim = int(decim)
new_sfreq = info['sfreq'] / float(decim)
lowpass = info['lowpass']
if decim > 1 and lowpass is None:
warn('The measurement information indicates data is not low-pass '
'filtered. The decim=%i parameter will result in a sampling '
'frequency of %g Hz, which can cause aliasing artifacts.'
% (decim, new_sfreq))
elif decim > 1 and new_sfreq < 3 * lowpass:
warn('The measurement information indicates a low-pass frequency '
'of %g Hz. The decim=%i parameter will result in a sampling '
'frequency of %g Hz, which can cause aliasing artifacts.'
% (lowpass, decim, new_sfreq)) # > 50% nyquist lim
offset = int(offset)
if not 0 <= offset < decim:
raise ValueError('decim must be at least 0 and less than %s, got '
'%s' % (decim, offset))
return decim, offset, new_sfreq
@fill_doc
class EvokedArray(Evoked):
"""Evoked object from numpy array.
Parameters
----------
data : array of shape (n_channels, n_times)
The channels' evoked response. See notes for proper units of measure.
info : instance of Info
Info dictionary. Consider using ``create_info`` to populate
this structure.
tmin : float
Start time before event. Defaults to 0.
comment : str
Comment on dataset. Can be the condition. Defaults to ''.
nave : int
Number of averaged epochs. Defaults to 1.
kind : str
Type of data, either average or standard_error. Defaults to 'average'.
%(verbose)s
See Also
--------
EpochsArray, io.RawArray, create_info
Notes
-----
Proper units of measure:
* V: eeg, eog, seeg, emg, ecg, bio, ecog
* T: mag
* T/m: grad
* M: hbo, hbr
* Am: dipole
* AU: misc
"""
@verbose
def __init__(self, data, info, tmin=0., comment='', nave=1, kind='average',
verbose=None): # noqa: D102
dtype = np.complex128 if np.iscomplexobj(data) else np.float64
data = np.asanyarray(data, dtype=dtype)
if data.ndim != 2:
raise ValueError('Data must be a 2D array of shape (n_channels, '
'n_samples), got shape %s' % (data.shape,))
if len(info['ch_names']) != np.shape(data)[0]:
raise ValueError('Info (%s) and data (%s) must have same number '
'of channels.' % (len(info['ch_names']),
np.shape(data)[0]))
self.data = data
self.first = int(round(tmin * info['sfreq']))
self.last = self.first + np.shape(data)[-1] - 1
self.times = np.arange(self.first, self.last + 1,
dtype=np.float64) / info['sfreq']
self.info = info.copy() # do not modify original info
self.nave = nave
self.kind = kind
self.comment = comment
self.picks = None
self.verbose = verbose
self.preload = True
self._projector = None
_validate_type(self.kind, "str", "kind")
if self.kind not in _aspect_dict:
raise ValueError('unknown kind "%s", should be "average" or '
'"standard_error"' % (self.kind,))
self._aspect_kind = _aspect_dict[self.kind]
def _get_entries(fid, evoked_node, allow_maxshield=False):
"""Get all evoked entries."""
comments = list()
aspect_kinds = list()
for ev in evoked_node:
for k in range(ev['nent']):
my_kind = ev['directory'][k].kind
pos = ev['directory'][k].pos
if my_kind == FIFF.FIFF_COMMENT:
tag = read_tag(fid, pos)
comments.append(tag.data)
my_aspect = _get_aspect(ev, allow_maxshield)[0]
for k in range(my_aspect['nent']):
my_kind = my_aspect['directory'][k].kind
pos = my_aspect['directory'][k].pos
if my_kind == FIFF.FIFF_ASPECT_KIND:
tag = read_tag(fid, pos)
aspect_kinds.append(int(tag.data))
comments = np.atleast_1d(comments)
aspect_kinds = np.atleast_1d(aspect_kinds)
if len(comments) != len(aspect_kinds) or len(comments) == 0:
fid.close()
raise ValueError('Dataset names in FIF file '
'could not be found.')
t = [_aspect_rev[a] for a in aspect_kinds]
t = ['"' + c + '" (' + tt + ')' for tt, c in zip(t, comments)]
t = '\n'.join(t)
return comments, aspect_kinds, t
def _get_aspect(evoked, allow_maxshield):
"""Get Evoked data aspect."""
is_maxshield = False
aspect = dir_tree_find(evoked, FIFF.FIFFB_ASPECT)
if len(aspect) == 0:
_check_maxshield(allow_maxshield)
aspect = dir_tree_find(evoked, FIFF.FIFFB_IAS_ASPECT)
is_maxshield = True
if len(aspect) > 1:
logger.info('Multiple data aspects found. Taking first one.')
return aspect[0], is_maxshield
def _get_evoked_node(fname):
"""Get info in evoked file."""
f, tree, _ = fiff_open(fname)
with f as fid:
_, meas = read_meas_info(fid, tree, verbose=False)
evoked_node = dir_tree_find(meas, FIFF.FIFFB_EVOKED)
return evoked_node
def _check_evokeds_ch_names_times(all_evoked):
evoked = all_evoked[0]
ch_names = evoked.ch_names
for ii, ev in enumerate(all_evoked[1:]):
if ev.ch_names != ch_names:
if set(ev.ch_names) != set(ch_names):
raise ValueError(
"%s and %s do not contain the same channels." % (evoked,
ev))
else:
warn("Order of channels differs, reordering channels ...")
ev = ev.copy()
ev.reorder_channels(ch_names)
all_evoked[ii + 1] = ev
if not np.max(np.abs(ev.times - evoked.times)) < 1e-7:
raise ValueError("%s and %s do not contain the same time instants"
% (evoked, ev))
return all_evoked
def combine_evoked(all_evoked, weights):
"""Merge evoked data by weighted addition or subtraction.
Each `~mne.Evoked` in ``all_evoked`` should have the same channels and the
same time instants. Subtraction can be performed by passing
``weights=[1, -1]``.
.. Warning::
Other than cases like simple subtraction mentioned above (where all
weights are -1 or 1), if you provide numeric weights instead of using
``'equal'`` or ``'nave'``, the resulting `~mne.Evoked` object's
``.nave`` attribute (which is used to scale noise covariance when
applying the inverse operator) may not be suitable for inverse imaging.
Parameters
----------
all_evoked : list of Evoked
The evoked datasets.
weights : list of float | 'equal' | 'nave'
The weights to apply to the data of each evoked instance, or a string
describing the weighting strategy to apply: ``'nave'`` computes
sum-to-one weights proportional to each object's ``nave`` attribute;
``'equal'`` weights each `~mne.Evoked` by ``1 / len(all_evoked)``.
Returns
-------
evoked : Evoked
The new evoked data.
Notes
-----
.. versionadded:: 0.9.0
"""
naves = np.array([evk.nave for evk in all_evoked], float)
if isinstance(weights, str):
_check_option('weights', weights, ['nave', 'equal'])
if weights == 'nave':
weights = naves / naves.sum()
else:
weights = np.ones_like(naves) / len(naves)
else:
weights = np.array(weights, float)
if weights.ndim != 1 or weights.size != len(all_evoked):
raise ValueError('weights must be the same size as all_evoked')
# cf. https://en.wikipedia.org/wiki/Weighted_arithmetic_mean, section on
# "weighted sample variance". The variance of a weighted sample mean is:
#
# σ² = w₁² σ₁² + w₂² σ₂² + ... + wₙ² σₙ²
#
# We estimate the variance of each evoked instance as 1 / nave to get:
#
# σ² = w₁² / nave₁ + w₂² / nave₂ + ... + wₙ² / naveₙ
#
# And our resulting nave is the reciprocal of this:
new_nave = 1. / np.sum(weights ** 2 / naves)
# This general formula is equivalent to formulae in Matti's manual
# (pp 128-129), where:
# new_nave = sum(naves) when weights='nave' and
# new_nave = 1. / sum(1. / naves) when weights are all 1.
all_evoked = _check_evokeds_ch_names_times(all_evoked)
evoked = all_evoked[0].copy()
# use union of bad channels
bads = list(set(b for e in all_evoked for b in e.info['bads']))
evoked.info['bads'] = bads
evoked.data = sum(w * e.data for w, e in zip(weights, all_evoked))
evoked.nave = new_nave
evoked.comment = ' + '.join(f'{w:0.3f} × {e.comment or "unknown"}'
for w, e in zip(weights, all_evoked))
return evoked
@verbose
def read_evokeds(fname, condition=None, baseline=None, kind='average',
proj=True, allow_maxshield=False, verbose=None):
"""Read evoked dataset(s).
Parameters
----------
fname : str
The file name, which should end with -ave.fif or -ave.fif.gz.
condition : int or str | list of int or str | None
The index or list of indices of the evoked dataset to read. FIF files
can contain multiple datasets. If None, all datasets are returned as a
list.
%(baseline_evoked)s
Defaults to ``None``, i.e. no baseline correction.
kind : str
Either 'average' or 'standard_error', the type of data to read.
proj : bool
If False, available projectors won't be applied to the data.
allow_maxshield : bool | str (default False)
If True, allow loading of data that has been recorded with internal
active compensation (MaxShield). Data recorded with MaxShield should
generally not be loaded directly, but should first be processed using
SSS/tSSS to remove the compensation signals that may also affect brain
activity. Can also be "yes" to load without eliciting a warning.
%(verbose)s
Returns
-------
evoked : Evoked or list of Evoked
The evoked dataset(s); one Evoked if condition is int or str,
or list of Evoked if condition is None or list.
See Also
--------
write_evokeds
"""
check_fname(fname, 'evoked', ('-ave.fif', '-ave.fif.gz',
'_ave.fif', '_ave.fif.gz'))
logger.info('Reading %s ...' % fname)
return_list = True
if condition is None:
evoked_node = _get_evoked_node(fname)
condition = range(len(evoked_node))
elif not isinstance(condition, list):
condition = [condition]
return_list = False
out = [Evoked(fname, c, kind=kind, proj=proj,
allow_maxshield=allow_maxshield,
verbose=verbose).apply_baseline(baseline)
for c in condition]
return out if return_list else out[0]
def _read_evoked(fname, condition=None, kind='average', allow_maxshield=False):
"""Read evoked data from a FIF file."""
if fname is None:
raise ValueError('No evoked filename specified')
f, tree, _ = fiff_open(fname)
with f as fid:
# Read the measurement info
info, meas = read_meas_info(fid, tree, clean_bads=True)
# Locate the data of interest
processed = dir_tree_find(meas, FIFF.FIFFB_PROCESSED_DATA)
if len(processed) == 0:
raise ValueError('Could not find processed data')
evoked_node = dir_tree_find(meas, FIFF.FIFFB_EVOKED)
if len(evoked_node) == 0:
raise ValueError('Could not find evoked data')
# find string-based entry
if isinstance(condition, str):
if kind not in _aspect_dict.keys():
raise ValueError('kind must be "average" or '
'"standard_error"')